摘要：This paper introduces a proposal for reservoir volume calculation in rainwater harvesting systems. The proposed method can be used for reservoir volume design in rainwater harvesting systems and is based on three important variables. These variables are water demand, system efficiency and repayment time. Several simulations were carried out in different scenarios considering typical values of both catchment area （for low-income and medium-income households） and water demand, with fixed water and tank costs. Results showed that the integrated analysis of demand, efficiency and repayment time may assist designers to determine a more adequate reservoir volume.

摘要：Analysis of variance (ANOVA) is a usual way for analysing experiments. However, depending on the design and/or the analysis scheme, it can be a hard task. ExpDes, acronym for Experimental Designs, is a package that intends to turn such task easier. Devoted to fixed models and balanced experiments (no missing data), ExpDes allows user to deal with additional treatments in a single run, several experiment designs and exhibits standard and easy-to-interpret outputs. It was developed at the exact sciences Institute of the Federal University of Alfenas, Brazil. Stable versions of package ExpDes are available on CRAN (Comprehensive R Archive Network) since 2012. Based on users’ feedback, the package was used to illustrate graduation and post-graduation classes and to carry out data analysis, in Brazil and many other countries. Package ExpDes differs from the other R tools in its easiness in use and cleanliness of output.